Vehicle exhaust apparatus and motorcycle equipped therewith

Abstract

In a vehicle exhaust apparatus constituting an exhaust passage to an exhaust muffler from a plurality of exhaust pipes connected to a multi-cylinder engine, an expansion chamber is formed on the way of the exhaust passage and is connected to an exhaust collector portion. The expansion chamber is formed so as to expand outward from the exhaust collector portion in a substantially arc or chevron shape when viewed from a direction substantially orthogonal to an exhaust gasflow. Preferably, the expansion chamber is formed in a spherical shape and plural branched exhaust pipes are formed on the exhaust gas downstream side of the expansion chamber.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a vehicle exhaust apparatus and a motorcycle equipped therewith, particularly to the vehicle exhaust apparatus constituting an exhaust passage to an exhaust muffler from plural exhaust pipes connected to a multi-cylinder engine, and the motorcycle equipped with the vehicle exhaust apparatus. [0003] 2. Description of the Related Art [0004] Some vehicle exhaust apparatuses connected to a multi-cylinder engine have a structure in which individual cylinder exhaust pipes connected to cylinders are independently connected to an exhaust muffler respectively. From the standpoints of compact piping space and exhaust gas pulsation attenuation, frequently the vehicle exhaust apparatus has a structure in -which plural exhaust passages are collected at the midpoint of an exhaust passage or a structure in which the exhaust passage is rebranched into plural exhaust passages after they are collected...

AI Technical Summary

Benefits of technology

[0010] In view of the foregoing, an object of the present invention is to enable smooth acceleration during acceleration in a low-speed range of the engine by following an acceleration operation by an operator of a vehicle without temporarily decreasing the engine torque, i.e., without generating a torque valley of the engine torque, and thereby maintaining a good operation feeling during the acceleration operation.

[0012] Since the expansion chamber whose inner peripheral surface is formed in the arc shape is connected onto the exhaust air downstream side of the exhaust collector portion as in the above configuration, exhaust gases of the engine are collected in the exhaust collector portion from the plural exhaust pipe and then, flows into the expansion chamber immediately after the exhaust gases are collected or pass through a short distance in the exhaust collector portion, the mutual inference of the exhaust gases is decreased and the generation of large back pressure is prevented. Therefore, the exhaust gas can smoothly flow through the exhaust passage and the generation of the torque valley in the low-speed range of the engine can be eliminated. That is, during acceleration in the low-speed range, the acceleration of the engine can be smoothly performed by following the acceleration operation by the operator without temporarily decreasing the torque, and thereby a good operation feeling can be maintained during the acceleration operation.

[0014] According to the above configuration, the whole of the exhaust gas collected in the exhaust collector portion from the plural exhaust passages flows rapidly and smoothly to the exhaust air downstream side along the inner surface of the spherical expansion chamber, so that the effect of eliminating the torque valley can be improved.

[0016] According to the above configuration, the expansion chamber can easily be arranged even in a space where the size is restricted in the vertical direction like the lower space of the engine of the motorcycle.

[0022] In an acceleration operation of the motorcycle, generally a rider of the motorcycle grasps and rotates a throttle grip, and rapid response (sense of unity) of the vehicle movement is required corresponding to the operation. Therefore, by providing the above-described vehicle exhaust apparatus to the motorcycle, the operation feeling is further improved by eliminating the torque valley during acceleration in the low-speed range of the engine. The compactness of the exhaust apparatus can also be maintained.

Problems solved by technology

This phenomenon gives a rider a feeling that power of the engine is temporarily lost.

That is, during the acceleration operation, because the torque is temporarily decreased against the rider's operation of accelerating, comfortable operation feeling cannot be obtained.

However, the expanded collector portion has little effect of eliminating the torque valley in the low-speed range.

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